A Passive Infrared (PIR) motion sensor is a device that detects infrared radiation emitted by moving objects or people within its field of view. Here’s a detailed description of a PIR motion sensor:

Principle of Operation: PIR motion sensors work on the principle of detecting changes in infrared radiation levels. Infrared radiation is emitted by all objects with a temperature above absolute zero. The sensor contains pyroelectric sensors that can detect these changes in infrared radiation when an object moves across its detection zone.
Detection Zone: The sensor has a specific detection area, often referred to as the “detection zone” or “field of view.” This is the region where it can detect motion and trigger a response.
Response and Output: When motion is detected within the detection zone, the PIR sensor generates an electrical signal, usually a voltage pulse or change in voltage level. This signal is then used to trigger an action, such as turning on lights, sounding an alarm, or activating a security system.
Sensitivity and Time Delay Adjustments: PIR sensors often have adjustable sensitivity and time delay settings. Sensitivity adjustments determine the level of motion needed to trigger the sensor, while time delay adjustments control how long the sensor remains active after detecting motion.